Question : TNEF decoding for junk mail filtering reasons

When tyrying to add a rule to my mailserver (hMailServer) so that any email with a particualr word (string) in it is deleted at the server-level, every once in a while an email gets through the rule. I am told that these messages are encoded in such a way that they are not text when they come into the server for "processing", so the string cannot be detected and the rule does not stop the message. After looking closely at these "emails that slip therough", they all have the string "X-MS-TNEF-Correlator: " in the header. What damage would there be in deleting all emails with this header?...would that be too many emails/how common is that header?...maybe I should auto-reply back with a "We don't accept TNEF encoded emails here...."-type email and then delete it?

Answer : TNEF decoding for junk mail filtering reasons

You will get a few messages with TNEF attachments but not a significant about. We receive about 500 genuine emails per day and we only get a few TNEF per week.

We use a (free) mail scanning piece of software called MailScanner which is able to strip out the attachments from TNEF files the vast majority of the time. When it cant it quarantines the messages and sends a mail to the sender saying its been quarantined.